pH-responsive double-enzyme active metal–organic framework for promoting the healing of infected wounds

The abuse of antibiotics accelerates the spread and evolution of drug-resistant bacteria, which seriously threatens human health. Hydroxyl radicals (•OH) are generated by peroxidase in the presence of H2O2, which is strongly oxidizing and can effectively kill bacteria. However, high production costs and poor stability limit the clinical use of natural enzymes. "Nanozyme" is a general term for nanomaterials with catalytic activity similar to that of biological enzymes. Compared to biological enzymes, nanozymes have the advantages of low cost, facile preparation, and easy storage, making them a good choice for the development of antibacterial agents. Here, a nickel-based metal–organic framework (Ni-MOF) with dual enzymatic activity that switches depending on the pH environment was studied. In a slightly acidic environment, Ni-MOF can react with hydrogen peroxide to produce hydroxyl radicals that kill bacteria; in a neutral environment, Ni-MOF instead removes excessive reactive oxygen species (ROS) and promotes the transformation of macrophages into M2 macrophages. Compared to most nanozymes, Ni-MOF has unique electrical conductivity and better biosafety. The results of animal experiments show that Ni-MOF can not only treat infected wounds but also promote the healing of acute wounds and exhibits great clinical application potential.